Numerical modelling of masonry arch bridges: Classical strategies and emerging approaches

Masonry arch bridges constitute a significant part of transport infrastructures in Europe, with thousands of structures in service today despite being designed more than a century ago through empirical bases. The strategic role of such structures combined with the need to account for updated load configurations (e.g. modern traffic loads and seismic actions) has stimulated the research on devoted analysis procedures. Over the last two decades the advancements in numerical and optimization techniques led to a variety of numerical strategies dedicated to masonry arch bridges. The problem is challenging, given the needs to properly take into account the properties of the masonry material, the interaction between the different structural elements (arch, backfill, piers, spandrels), and finally the critical aspects of such structures. In this work, a comprehensive review of the numerical modelling approaches dedicated to masonry arch bridges is presented. Such approaches are discussed by considering the following main categories: thrust line-based methods, rigid block analysis, discontinuity layout optimization, discrete elements- and finite elements-based methods. Highlights on future perspectives and open problems are also provided.